The present invention relates to a linerless pressure-sensitive label construction in which plural label sheets printed with pertinent data are pasted on one another without using a release liner, so that by peeling off the label sheets from each other, each sheet can be used as a label.
The prior art pressure-sensitive labels comprise label sheets that are provided with adhesive on the back and that are each pasted on the surface of a release liner. To use the label sheets, each sheet is peeled off from the release liner and pasted on a product or a container. The release liner of such label sheet therefore serves merely as a support which protects the adhesive on the label sheet until the label sheet is peeled off and pasted on a product or container. After the label sheet is used for its intended purpose, the release liner is discarded.
However, the release liner is usually made from relatively expensive glassine paper or super-calendered kraft paper of closely arranged short fibers in order to prevent the release material such as silicone which is coated on the release liner from unnecessarily permeating into fibers of the paper. It would therefore be highly uneconomical in terms of conservation of resources to discard such expensive paper after the label sheets are used.
To eliminate the release liner, reduce the cost of pressure-sensitive labels, and provide sheets of labels from which individual labels may be detached easily, linerless pressure-sensitive labels are known in the art such as disclosed in U.S. Pat. No. 3,312,005 (McElroy). According to McElroy, as shown in FIG. 9 of the present application, strips 4 and 5 of release material are provided on the back of label sheets 1 and 2 at a given interval and are arranged in a positionally staggering manner. The label sheets 1 and 2 are respectively coated with adhesive 3 on their back and then pasted together.
Thus, as shown in FIG. 10 of the present application, when the label sheets 1 and 2 are detached from each other, strips of adhesive 3a on one of the label sheets 1 are peeled off from the corresponding strips 5 of release material of the other label sheet 2. Likewise, strips of adhesive 3b of the other label sheet 2 are also peeled off from the corresponding strips 4 of release material. In this way, the peeled apart label sheets 1 and 2 can be used for their original intended purposes.
Labels of this type do not require a lining of release paper on their back. By detaching the label sheets that are pasted together, these label sheets can be fully utilized without any waste and are therefore most economical. However, such economical labels are not fully utilized today because of the following reasons. Strips of adhesive 3a, 3b of one of the label sheets 1 or 2 are contacted with the strips of release material 4 or 5 of the other label sheet, allowing detaching of the sheets from each other. However, strips of adhesive 3a of the label sheet 1 and the strips of adhesive 3b of the label sheet 2 which come adjacent to the former when pasted together are actually in one continuous form, as shown in FIG. 9 of the present application. Thus, when the label sheets 1 and 2 are detached from each other, the portions of adhesive 3a and adhesive 3b constituting one continuous member cannot be severed into well defined strips. The boundaries 3c between these strips are forcibly cut off, causing threading 6 from both of the strips 3a and 3b, as shown in FIG. 10 of the present application.
When the strips of adhesive 3 cannot be adequately severed at the boundaries between the strips 4 and 5 of the release material to thereby cause threading 6 of the adhesive, the surface of the severed strips 3a, 3b of adhesive 3 will become untidy and coarse. Moreover, because it requires force to pull apart the strips of adhesive 3a and 3b, the label sheets 1 and 2 cannot be smoothly detached from each other like the general purpose labels using release paper and the appearance of the label as a product is severely damaged. The inadvertent threading 6 hanging from the label edge would adhere on the surface of an object to which the label is to be attached, leaving bumps on said surface and thus greatly damaging the appearance of the label when attached.